WO 2004/047659 and WO 2005/115235 relate to apparatus for generating microwave energy suitable for enabling controllable ablation of cancerous tissue using dynamic impedance matching and for making tissue state measurements. In practice, for the controlled ablation/tissue state measurement system to operate efficiently it is desirable to perform dynamic impedance (or energy) matching with the changing tissue load during the process of ablation and measurement of small changes in complex impedance to enable characterisation of various tissue types, tissue states and/or stages associated with the growth of cancerous tumours to be measured.
Conventional antenna structures can be inefficient when used with such systems.